Here is the way to make Billions of dollars every week, virtually making every other method of income irrelevant. Create at least 5 alternate accounts. These are theoretically illegal according to Pixel Addicts, but there are dozens and dozens of them. Have each one create a clan and put one player in it in addition to the leader (I've heard him called a paperweight). When boss begins, have 2 players boost, 4X is best, but whatever. Have these two supertappers hop from clan to clan and do 4-6 bosses each. With the boost, and multiple devices (remember your alternate accounts require one device each), you can do this pretty quickly. Your 2 players have each earned 20-36 boss items and around $30 billion. Each alternate account has also made $30 billion. they each ship their winnings to the master account, to arrive in 1-2 weeks. Net income, if evenly split between the 2 tappers is $45 billion per boss. Oh, plus the 20-36 boss items. Still think you should invest in a city? My city makes almost a billion per day. It feels like tip money.